PROJECT SUMMARY Our lab works on two main directions: ?rst, the determination of the structural and dynamic basis for the function and assembly of large protein machineries; and second, the determination of the role of internal protein dynamics in regulating protein activity and allosteric interactions. We propose to use NMR spectroscopy, together with other biochemical and biophysical techniques, to determine at the atomic resolution the mechanisms underpinning the function of two important protein families: molecular chaperones and protein kinases. Molecular chaperones are central to maintaining a functional proteome in the cell by rescuing non- native proteins from aggregation and misfolding and assisting with their folding. Our lab reported the ?rst ever high resolution structures of molecular chaperones in complex with unfolded proteins. We will determine the structures of important chaperones such as the Hsp40, Hsp70 and Hsp90 in complex with client proteins. We wish to address how different chaperones engage non-native proteins and how distinct chaperone architectures may alter activity. The Abl kinase holds a prominent place among the over 500 protein kinases encoded by the human genome. Abl mediates its function by participating in a number of biological processes, including actin remodeling, cell adhesion and motility, DNA damage response, and bacterial pathogen response. The Bcr-Abl fusion gene product has constitutive tyrosine kinase activity and causes chronic myeloid leukemia (CML). We will use NMR to provide fascinating, novel information about the regulatory and activation mechanisms of this important kinase. We will study how drug-resistance mutations exert their effect in lowering the drug af?nity for Abl.